Method for determining occupancy status within a motor vehicle - Patents.com

Abstract

The present invention relates to a method for determining an occupancy state in a motor vehicle (40) using an occupancy sensor (10), comprising the steps of periodically determining the occupancy state and determining a value representative of a vibration magnitude of the vehicle using a vibration sensor (20). According to the invention, the method comprises a step of interrupting the periodic determination of the occupancy state, the interruption being triggered based on the value representative of the vibration magnitude.

Description

[Technical Field]

[0001] The present invention relates generally to detecting people in vehicles.

[0002] More particularly, the present invention relates to a method for determining occupancy within a motor vehicle.

[0003] The invention can be applied in a particularly advantageous manner in warning applications regarding the presence of forgotten children or fastening of safety belts.

[0004] The invention also relates to a system for implementing such a method. [Background technology]

[0005] Presence detection systems using radar are increasingly being integrated into motor vehicles. The use of radar is a promising alternative because it is less costly to implement than conventional techniques based on weight sensors integrated into every seat of the vehicle.

[0006] Presence detection can be used, for example, to provide a forgotten child warning in a locked vehicle or to remind passengers to lock their safety belts.

[0007] In addition to the movement caused by driving, vehicles are also subject to vibrations due to external factors. This can occur when the vehicle is stationary, for example due to air currents, whether natural, generated by another vehicle passing nearby, or during repairs or cleaning. This can also occur in driving situations, for example as a result of road irregularities or the movement of passengers inside the vehicle.

[0008] These vibrations can disrupt radar operation, for example by causing movement of objects that are normally fixed, such as seats, which can inadvertently cause false detection of people.

[0009] Therefore, there is a clear need to make radar presence detection systems more robust to vehicle vibrations. Summary of the Invention

[0010] In this regard, the present invention provides a method for determining occupancy in a motor vehicle using a presence sensor, the method comprising: periodically determining an occupancy state; determining a value representative of an amount of vibration of the vehicle; interrupting a periodic determination of occupancy triggered based on a value representative of the amount of vibration; A method is proposed which includes:

[0011] Thus, as a result of the present invention, vibrations experienced by a vehicle are quantified by a value representing the amount of vibration of the vehicle. By suspending presence detection based on this quantification, false detections due to vibrations can be advantageously eliminated. In fact, if the vibrations are too great, presence detection is suspended as it may generate false detections.

[0012] Notably, the interruption of detection during vibration has little impact on the functionality of the presence detection system, since it only causes a slight time delay in any warnings regarding, for example, a forgotten child or a seat belt, while the interruption of detection during vibration allows to avoid false detections, which are usually accompanied by annoying audio signals.

[0013] Other advantageous, non-limiting features of the method for determining an occupancy state according to the invention, considered individually or in any technically possible combination, are: During the interruption, the occupancy state is considered to be identical to the last occupancy state determined before the interruption; the decision interruption is triggered when the value representing the amount of vibration exceeds a first predetermined threshold or when a change in the value representing the amount of vibration exceeds a second predetermined threshold, the method further comprises a step of resuming the periodic determination of the occupancy state, the resumption being triggered based on a value representative of the amount of vibration; the restarting step includes the substep of reinitializing the presence sensor; When a resume step is triggered, the occupancy state is initially determined as the last occupancy state determined before the interruption, the resumption of the periodic determination is triggered when the value representing the amount of vibration falls below a third predetermined threshold or when the change in the value representing the amount of vibration falls below a fourth predetermined threshold; the periodic determination of the occupancy state consists in repeating said determination at regular time intervals, The method further includes transmitting a signal based on a state of presence, the signal indicating that an occupant is present in a stationary locked vehicle, or that the occupant needs to fasten a safety belt, or that an airbag needs to be deactivated; an occupancy state is determined for at least one of the seats of the vehicle, the occupancy state including an occupied state in which an occupant is seated in the seat and an unoccupied state in which the seat is unoccupied; the value representing the amount of vibration is calculated as a weighted sum of the acceleration of the vehicle along a first axis and the acceleration of the vehicle along a second axis different from the first axis; The weighting coefficients of the sum are selected based on at least one of the following causes of vehicle vibration: air flow; movement of the vehicle during maintenance or repair; an outside person pushing the vehicle; passage of the vehicle through a washing system; defects in the road on which the vehicle is traveling; and occupants moving within the vehicle.

[0014] The present invention also provides a system for determining occupancy within a motor vehicle, comprising: a presence sensor adapted to periodically determine an occupancy state; a vibration sensor adapted to determine a value representative of an amount of vibration of the vehicle; a computer coupled to the presence sensor and the vibration sensor and programmed to interrupt periodic determination of occupancy based on a value representing the amount of vibration; We propose a system that includes the following.

[0015] Other advantageous, non-limiting features of the system for determining occupancy according to the invention, considered individually or in any technically possible combination, are: The vibration sensor is included in an electronic card that also includes a presence sensor, The vibration sensor is included and used in another system of the vehicle.

[0016] It will be appreciated that different features, variations and embodiments of the invention may be associated with one another in various combinations, unless they are incompatible or mutually exclusive. DETAILED DESCRIPTION OF THE INVENTION

[0017] The following description, with reference to the accompanying drawings, given as non-limiting examples, will give a better understanding of what the invention consists of and how it can be put into practice. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a schematic cross-sectional view of a vehicle incorporating a system for determining occupancy according to the present invention; [Figure 2] 1 is a block diagram of a series of steps for implementing a method for determining occupancy according to the present invention; [Figure 3] 3 is a graph showing the occupancy state over time determined using the method of FIG. 2; [Figure 4] 4 is a graph showing the time variation of a value representing the amount of vibration determined according to the method of FIG. 2, accompanied by the time variation of the occupancy state of FIG. 3;

[0019] 1 shows a system 1 according to the invention for determining the occupancy state E of an occupant 50 in a vehicle 40, in this case a motor vehicle. The system 1 comprises: a presence sensor 10; a vibration sensor 20; a computer 30 connected to the presence sensor 10 and the vibration sensor 20; Equipped with.

[0020] The presence sensor 10 is adapted to determine the presence of an occupant 50 in the vehicle 40. In this case, the presence sensor 10 is adapted to determine the presence of a person, i.e., the driver or passenger, more generally, for each seat 41 of the vehicle 40. A single occupant 50, in this case the driver, is shown in Figure 1. The presence sensor 10 is not only able to determine the presence on the seat 41, but also covers the trunk and the area adjacent to the seat, typically the leg well located below the seat 41.

[0021] By placing the presence sensor 10 in the central region of the vehicle 40, in this case in the center of the roof 42 of the vehicle 40 as shown in FIG. 1, the presence sensor 10 can advantageously cover all seats 41 of the vehicle 40.

[0022] The presence sensor 10 may be any device that allows for the determination of the presence of an occupant 50 within the vehicle 4. The presence sensor 10 may consist of a single sensing element or a network of sensing elements distributed throughout the vehicle 40.

[0023] The presence sensor 10 may for example be a camera or a camera network, or an ultrasonic sensor or a network of ultrasonic sensors.

[0024] In this case, the presence sensor 10 is a device for transmitting and receiving waves, these waves being, for example, sound waves.

[0025] In this case, these waves are electromagnetic waves 11. The transmitter / receiver device in this case comprises an antenna (not shown) designed to transmit the electromagnetic waves 11 and at least one receiver (not shown) designed to receive reflected electromagnetic waves 12 after reflection of the electromagnetic waves 11, in particular after reflection from the occupant 50.

[0026] The transmitter / receiver device in this case is more specifically a radar (radio detection and ranging) using millimeter-wave electromagnetic waves, such as a continuous wave Doppler radar, the same type of radar used in the vehicle 40 for driving assistance and / or obstacle detection.

[0027] The computer 30 comprises at least one memory and at least one processor. The computer 30 may be, for example, an electronic control unit (ECU) of the vehicle 40. The computer 30 may also be a computer dedicated to the system 1. Instructions for determining the occupancy state E are recorded in the memory and executed by the processor. When executed, these instructions enable the execution of the methods described below.

[0028] In particular, the computer 30 is programmed to control the transmitter / receiver device, in particular to control the transmission of the electromagnetic waves 11 .

[0029] By analyzing the reflected electromagnetic waves 12 captured by the sensors of the transmitter / receiver device, the computer 30 determines, in this case for each seat 41, an occupancy state E indicating whether the seat 41 is occupied or vacant. An occupancy state E may also be determined for the trunk of the vehicle 40, and an indication may be given as to whether an occupant 50 is present in the trunk.

[0030] For each seat 41, and in this case its vicinity, the occupancy state E includes an occupied state in which an occupant 50 is seated in the seat 41 or is located in close proximity to the seat 41, for example slightly above the seat 41, and an unoccupied state in which no one is seated in the seat 41 or located in close proximity to the seat 41. Thus, the unoccupied state corresponds to the occupancy state E in which the seat 41 is unoccupied.

[0031] The vibration sensor 20, for its part, makes it possible to measure the acceleration of the vehicle 40 along at least one axis. As with the presence sensor 10, the vibration sensor 20 can also comprise one or more elements distributed within the vehicle, where one element of the vibration sensor 20 is located in the vicinity of each sensing element of the presence sensor 10, preferably on the same electronic circuit card as this sensing element.

[0032] The vibration sensor 20 may be, for example, a fiber optic gyroscope.

[0033] Here, the vibration sensor 20 is more specifically an accelerometer.

[0034] The accelerometer in this case is a Micro-Electro-Mechanical System (better known by the acronym MEMS). In a variant, the accelerometer may be a piezoelectric accelerometer.

[0035] The accelerometer in this case is fixed to the vehicle 40, in particular to its bodywork. Thus, in the example shown in Figure 1, the accelerometer is located on the roof 42 of the vehicle 40. Here, although shown separately from the transmitter / receiver device in Figure 1, the accelerometer 30 is included on an electronic circuit card that also includes the transmitter / receiver device. In a variant, the accelerometer is included in and used by another system of the vehicle, for example a wheel antilock system or an airbag control system. The accelerometer is, for example, located on the instrument panel of the vehicle.

[0036] Here, the accelerometer allows for measuring the acceleration of the vehicle 40 along three orthogonal axes. As shown in Figure 1, these three axes are, for example, a vertical direction A1 (perpendicular to the road), a longitudinal direction A2 of the vehicle 40, and a lateral direction A3 of the vehicle 40.

[0037] The accelerometer is therefore adapted to determine a value representative of the vibration magnitude of the vehicle 40. This value representative of the vibration magnitude of the vehicle 40, hereinafter referred to as vibration value V, is for example expressed in milli-g, i.e. thousandths of a g, the value of g being approximately 9.8 m / s 2 is.

[0038] Here, the vibration value V represents the intensity of the vibrations experienced by the vehicle 40, i.e., the amplitude and / or speed of the movement of the vehicle 40 around the equilibrium position of the vehicle 40 when it is stationary and immovable, or when it is moving forward at a constant speed. In practice, the movement of the vehicle 40 around its equilibrium position is a movement of a few millimeters or centimeters.

[0039] The vibrations experienced by the vehicle 40 and quantified using the vibration value V are here generated by external events that cause the vehicle 40 to move. In this case, "external" is taken to mean events that are not caused by the vehicle 40 itself, e.g., events that are not caused by the movement of the vehicle by its engine. Examples of external events that generate vibrations 40 are: air flow; Movement of vehicles during maintenance or repairs; Outside person pushing vehicle 40; Passage of vehicles through the washing system; Defects in the road surface on which the vehicle is traveling; Passengers moving around inside the vehicle.

[0040] In system 1, computer 30 is also programmed to control the accelerometers, particularly for the purpose of determining a vibration value V based on the output signals of the accelerometers.

[0041] In practice, the system 1 determines the occupancy state E by detecting the shifts or movements of the occupant 50, including breathing or heartbeat. This detection is accurate due to the use of short electromagnetic waves, but is sensitive to vibrations of the vehicle 40.

[0042] To prevent false detections, the computer 30 is programmed to implement a method for determining the occupancy state E, which can interrupt the determination of the occupancy state E based on vibrations experienced by the vehicle 40. A method according to the invention is illustrated in FIG.

[0043] As shown in FIG. 2, the method includes the following main steps: a step e1 of periodically determining an occupancy state E using a transmitting / receiving device; a step e2 of determining a vibration value V; A step e3 of interrupting the periodic determination of the occupancy state E, triggered on the basis of the vibration value V.

[0044] Here, "periodically" means "repeatedly" and "automatically." More specifically, the determination of the occupancy state E is repeated here at regular time intervals, for example every 10 seconds. The regular time intervals are, for example, less than one minute. Preferably, the regular time intervals are 3 to 5 seconds. The regular time intervals may be adapted based on the detected movements of the occupant 50, for example, 5 seconds before respiratory movements and 4 seconds for head movements.

[0045] Advantageously, the computer 30 can be programmed to adapt the frequency of repetition of the periodic determination based on the use taking place in the occupancy state E, i.e., indication of a forgotten child or indication of fastening a safety belt, etc.

[0046] In a variant, periodic determination of the occupancy state may mean that the occupancy is determined at short but irregular time intervals, but on the other hand these time intervals may follow a predetermined recurrence schedule.

[0047] The vibration value V is determined by an accelerometer. Here, the vibration value V is also determined periodically. For example, the vibration value V is determined at the same frequency as the occupancy state E. The vibration value V may also be determined at a frequency other than the frequency used for the occupancy state E. Preferably, the determination of the vibration value V is repeated at regular time intervals of less than one minute. Here, for example, the determination of the vibration value V is repeated every 50 milliseconds.

[0048] Here, the suspension consists in temporarily suspending the periodic determination of the occupancy state E. In other words, once the suspension is initiated, the occupancy state E is not determined until the resumption step e4.

[0049] The interruption of the periodic determination of the occupancy state E is triggered based on the vibration value V. Thus, if the vibration value V is, for example, too high or increases too rapidly, the periodic determination of the occupancy state E is interrupted to avoid a false presence detection, where a false presence detection means determining the occupancy state E as occupied when the seat 41 and / or its vicinity (e.g., foot-height space) is not occupied.

[0050] Suspending the determination of occupancy state E is a robust and easily implemented means of avoiding false positives. Furthermore, suspending the determination of occupancy state E allows computer 30 to act with very short reaction times as soon as vibrations are measured.

[0051] Next, the major steps mentioned above can be explained in detail.

[0052] As shown in FIG. 2, the step e1 of periodic determination of the occupancy state E includes the following substeps: a substep e11 of transmitting electromagnetic waves 11 via an antenna; a substep e12 of receiving reflected electromagnetic waves 12 via a sensor; Substep e13 of analyzing the reflected electromagnetic wave 12 by the computer 30 to determine the occupancy state E.

[0053] Here, as shown schematically in FIG. 2, after the occupancy state E is determined by a first cycle of transmitting, receiving and analyzing, the occupancy state E may be redetermined by a new cycle of transmitting, receiving and analyzing.

[0054] Thus, here, the periodic determination of the occupancy state E means that in particular the substep e11 of transmitting the electromagnetic wave 11 is carried out periodically. Then, the other two substeps of receiving e12 and analyzing e13 are included in this chain, again periodically.

[0055] In a variant, the transmitting and receiving substeps are repeated periodically more frequently than the determination of the occupancy state, for example by analysing a plurality of reflected electromagnetic waves to determine the occupancy state.

[0056] In FIG. 3, the step e1 of periodically determining the occupancy state E is carried out over a first repetition period T1 and a second repetition period T4.

[0057] 3, the occupancy state E can vary between an occupied state, to which the computer 30 assigns the numerical value 1, and an empty state, to which the computer 30 assigns the numerical value 0. Here, the occupancy state E also includes an obstructed state, to which the computer 30 assigns the numerical value 2, when the transmitting / receiving device is obstructed, for example, by hand, making it impossible to determine the occupancy state E.

[0058] The repetition of the determination of the occupancy state E is illustrated in FIG. 2 by the successive changes in the numerical value assigned to the occupancy state E during a first repetition period T1 and a second repetition period T4.

[0059] The vibration value V is calculated by the computer 30 as a weighted sum of the acceleration of the vehicle 40 along at least two different axes. Here, the vibration value V is calculated as a weighted sum of the acceleration of the vehicle 40 in the vertical direction A1, the longitudinal direction A2, and the lateral direction A3. Each direction A1, A2, A3 is then associated with a weighting factor. Obviously, the vibration value V may be the result of vibration in a single axis, which may be sufficient to interrupt the periodic determination.

[0060] The weighting of this sum can be adapted based on external events that generate vibrations in the vehicle 40. So, for example, if the vehicle 40 is parallel parked along a road, it may vibrate laterally due to airflows generated by other vehicles. In this case, a high weighting factor for acceleration in other directions, particularly the longitudinal direction A2, can be applied by the computer 30 to the acceleration in the lateral direction A3, thereby effectively limiting false detections due to such external events.

[0061] The weighting of this sum may be adapted based on the use performed in occupancy state E, such as warning of a forgotten child, instruction to fasten a safety belt, etc. Here, the weighting of the sum is predetermined, i.e., selected before the implementation of the method, in order to detect the smallest vibrations associated with the aforementioned external events that may cause false detections.

[0062] When the vibration value V is determined, it enables the computer 30 to trigger an interruption of the determination of the occupancy state E.

[0063] To this end, in a first variant embodiment, the computer 30 compares the vibration value V with a first predetermined threshold value P. If the vibration value V is greater than the first predetermined threshold value P, or for example significantly greater than the first predetermined threshold value P, the computer 30 interrupts the periodic determination of the occupancy state E.

[0064] Thus, in the example shown in FIG. 4, the moment when the vibration value V becomes greater than the first predetermined threshold P indicates a change from a first repetition period T1, during which the determination of the occupancy state E is periodic, to an interruption period T2, during which the determination of the occupancy state E is interrupted.

[0065] Preferably, in the second variant, the computer 30 compares the time change of the vibration value V, i.e., the time derivative of the vibration value V, with a second predetermined threshold. If the derivative of the vibration value V is greater than the second predetermined threshold, e.g., significantly greater, the computer 30 interrupts the periodic determination of the occupancy state E. Here, the frequency of the determination of the vibration value V is high, e.g., less than 2 seconds, so that an accurate derivative can be calculated. Since the frequency of the determination of the vibration value V is significantly high during the first iteration, a calculation log can be created.

[0066] The first predetermined threshold P or the second threshold P can be adjusted to limit false detections more or less. The first predetermined threshold P is, for example, 0.3 to 0.5 milligrams. The second predetermined threshold P is, for example, a 2 milligram change over a 60 millisecond interval.

[0067] Here, the vibration curves and their time evolution are obtained for a test sequence of various external events as described above, and the first and second thresholds P and E can then be determined from these curves based on the influence of the external events on the detection of the occupancy state E.

[0068] The interruption can consist, for example, in pausing the transmission of the electromagnetic waves 11 or in pausing the analysis of the reflected electromagnetic waves 12, as shown in FIG.

[0069] It is worth noting that during the interruption period T2, the occupancy state E is considered to be equal to the last occupancy state E determined before the interruption. In other words, the computer 30 stores in its memory the last occupancy state E determined before the interruption. The last occupancy state E is, for example, the one determined in the transmit / receive / analyze cycle preceding the moment when the vibration value V becomes greater than the first predetermined threshold P.

[0070] Thus, in the example shown in Figures 3 and 4, when the interrupt is triggered, the occupancy state E retains its last value obtained during the first repetition period T1, i.e. the numeric value 1 associated with the occupancy state.

[0071] Retaining the last value of occupancy state E allows functions of vehicle 40 to continue to operate based on occupancy state E when occupancy state E is determined at a steady state. However, now, the occupancy value is not retained if the vehicle doors undergo opening and closing operations, as this may indicate a change in the number of occupants in vehicle 40.

[0072] In a variant, during the suspension period the occupancy state can be automatically fixed to one of two states, for example "vacant" for the forgotten child alert function.

[0073] When the determination of the occupancy state E is interrupted, the step e2 of determining the vibration value V continues to be performed periodically. For example, the vibration value V continues to be determined over a time interval T2. In the illustrated example, the vibration value V remains constant, indicating that the vehicle 40 is vibrating with a constant intensity.

[0074] The interruption therefore consists in temporarily halting the periodic determination of the occupancy state E for the duration of one oscillation.

[0075] As shown in Figure 2, the method now includes an auxiliary step e4 of resuming the periodic determination of the occupancy state E. Similar to the interruption, the resumption is triggered based on the vibration value V. The resumption consists in starting again to periodically determine the occupancy state E.

[0076] Resumption therefore makes it possible to determine the occupancy state E when the vibration that triggered the interruption has ceased, and therefore based on a stable signal generated by the transmitting / receiving device.

[0077] For this purpose, similar to the interruption, the resumption of the periodic determination is triggered, for example, when the vibration value V falls below a third predetermined threshold, which is the case, for example, in the example shown in Figure 4. The third predetermined threshold is, for example, equal to the first predetermined threshold P.

[0078] Preferably, the resumption of the periodic determination is triggered, for example, when the derivative of the vibration value V falls below a fourth predetermined threshold, for example equal to the second predetermined threshold.

[0079] As shown in FIG. 2, the restart step e4 now comprises a single step e41 of reinitializing the transmitter / receiver device.

[0080] The reinitialization generates a waiting period T3, which here corresponds to a complete transmit / receive / analyze cycle for the determination of the occupancy state E. The initialization makes it possible to avoid determining the occupancy state E on the basis of a radar signal that is likely to be disturbed by oscillations during the transmit / receive / analyze cycle.

[0081] During the waiting period T3, the occupancy state E is again considered to be equal to the last occupancy state E determined before the interruption. Thus, when the restart step e4 is triggered, the occupancy state E is initially determined as the last occupancy state E determined before the interruption, during a short period of time corresponding to the waiting period T3.

[0082] Thus, in the example of FIG. 3, during the waiting period T3, computer 30 continues to treat occupancy state E as equal to the occupancy state that was the last occupancy state E determined before the interruption.

[0083] After the waiting period T3, the computer 30 resumes periodic determination of the occupancy state E. Now, immediately after the waiting period T3 and before the first determination of the occupancy state, the first determination of the occupancy state is initially indeterminate (state not shown) and therefore does not trigger a false detection.

[0084] 3, upon completion of the reinitialization, i.e., at the beginning of the second repeat period T4, the occupancy state E is initially determined as empty. Thereafter, the occupancy state E is determined as occupied, and its value changes from 0 to 1. The computer 30 resumes the periodic determination of the occupancy state E over the second repeat period T4, for example, until a new interruption.

[0085] Finally, as shown in Figure 2, the method now includes a step e5 of transmitting a signal based on the occupancy state E. The signal here is a warning signal, for example an audible signal intended for the occupant 50 or the holder of the key to the vehicle 40.

[0086] The signal may indicate, for example, the presence of an occupant 50 in a stationary, locked vehicle, or that the occupant 50 should fasten their safety belt. The signal may also be an airbag deactivation signal that triggers for a particular type of occupant 50.

[0087] The present invention is in no way limited to the embodiments described and shown, but a person skilled in the art will know how to add to these any variants according to the invention.

Claims

Claim 1: A method for determining an occupancy state (E) within a motor vehicle (40) using a presence sensor (10) including a radar, comprising: a step (e1) of periodically determining said occupancy state (E) using said radar; and (e2) determining a value (V) representative of the amount of vibration of the vehicle (40), The method comprises a step (e3) of interrupting the periodic determination of the occupancy state (E) by the radar during vibrations, the interruption being triggered based on the value (V) representing the amount of vibration.

2. 2. The method of claim 1, wherein during said interruption, said occupancy state (E) is considered to be equal to the last occupancy state (E) determined before said interruption.

3. 2. The method of claim 1, wherein the interruption of the determination is triggered when the value (V) representing the amount of vibration becomes greater than a first predetermined threshold (P) or when a change in the value (V) representing the amount of vibration becomes greater than a second predetermined threshold.

4. 2. The method of claim 1, further comprising a step (e4) of resuming the periodic determination of the occupancy state (E), wherein the resumption is triggered based on the value (V) representing the amount of vibration.

5. 5. The method of claim 4, wherein the restarting step (e4) comprises a substep (e41) of reinitializing the presence sensor (10).

6. 5. The method of claim 4 when dependent on claim 2, wherein when the resuming step (e4) is triggered, the occupancy state (E) is initially determined as the last occupancy state (E) determined before the interruption.

7. 5. The method of claim 4, wherein the resumption of the periodic determination is triggered when the value (V) representing the amount of vibration falls below a third predetermined threshold or when a change in the value (V) representing the amount of vibration falls below a fourth predetermined threshold.

8. 2. The method according to claim 1, wherein said periodic determination of said occupancy state (E) consists in repeating said determination at regular time intervals.

9. 2. The method of claim 1, further comprising the step (e5) of transmitting a signal based on the occupancy state (E), the signal indicating that an occupant (50) is present in the vehicle (40) that is stationary and locked, or that the occupant (50) needs to fasten a safety belt, or that an airbag needs to be deactivated.

10. 2. The method of claim 1, wherein the occupancy state (E) is determined for at least one seat (41) of the vehicle (40), and the occupancy state (E) includes an occupied state in which a passenger (50) is seated in the seat (41) and an empty state in which the seat (41) is not occupied.

11. 2. The method of claim 1, wherein the value (V) representing the amount of vibration is calculated as a weighted sum of an acceleration of the vehicle (40) along a first axis (A1, A2, A3) and an acceleration of the vehicle (40) along a second axis (A1, A2, A3) different from the first axis (A1, A2, A3).

12. The weighting coefficients of the sum are calculated based on the following causes of vibration of the vehicle (40): Air flow; Movement of said vehicle (40) during the course of maintenance or repair; an outside person pushing the vehicle (40); Passage of said vehicle (40) through a washing system; imperfections in the road surface on which the vehicle (40) is traveling; A passenger (50) moving within the vehicle (40) The method of claim 11 , wherein the selected area is selected based on at least one of the following:

13. 1. A system for determining an occupancy state (E) in a motor vehicle (40), comprising: a presence sensor (10) including a radar adapted to periodically determine said occupancy state (E); a vibration sensor (20) adapted to determine a value (V) representative of the amount of vibration of said vehicle (40); a computer (30) connected to the presence sensor (10) and the vibration sensor (20); The computer (30) is programmed to suspend the periodic determination of the occupancy state (E) by the radar during vibration based on the value (V) representing the amount of vibration.

14. 14. The system of claim 13, wherein the vibration sensor (20) is included on an electronics card that also includes the presence sensor (10).

15. 14. The system of claim 13, wherein the vibration sensor (20) is included in and used with another system of the vehicle (40).

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